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the trial, in December 2012, the two machines were achieving an average out- put of 415 mt/h, Atlas Copco reported, and were outperforming manually operated LHDs on a monthly production basis. Meanwhile, Andina is also the venue for the current evaluation program on Caterpillar's Rock Flow system, which was described in the June 2013 edition of E&MJ; (pp. 56–61). Harnessing armored face conveyor concepts from longwall coal mining, the system is fully automated with real-time draw control and transport from the drawpoints to primary crushing units. Speaking at ExpoMin 2012, the head of the Rock Flow project for Caterpillar, Markus Frenzel, gave some details of achievements from the first proof-of-con- cept trials at Codelco's Salvador mine. Here, four Rock Feeders were used in con- junction with a 75-m-long Rock Mover chain conveyor rated at 900 mt/h capacity. In fact, Frenzel said, the system handled more than 122,000 mt of ore during the trial, with the 300-mt/h-rated Rock Feeders averaging 260 mt/h. The Andina trial has been designed as the first industrial-scale basis for the equipment, with 32 Rock Feeders delivering ore on to four parallel Rock Movers. This gives a nom- inal capacity of 3,600 mt/h, with the aim of ramping up production to around 150,000 mt/month. Servicing on the Rock Feeders is done from access drifts driven between the production haulages. The system is currently being installed, with commissioning sched- uled for December, Frenzel said. Major benefits claimed for the system include lower ventilation requirements, with no diesel-engined equipment needed. Personnel are only required for mainte- nance, with the system being controlled remotely. With the future development of high-capacity "super caves," Caterpillar believes that production based on LHDs will be constrained by their carrying capacity and the sheer volume of traffic; hence its interest in applying an alternative approach to draw- point management and rock haulage. Looking Ahead In one of the keynote presentations at the Caving 2014 conference, German Flores from Newcrest Mining sounded a warning call that although block- and panel-caving technology has achieved significant develop- ments over the past 30 years, the challenges ahead may require some new thinking. "The evolution of the cave-mining industry has been driven by the require- ment to adapt to change," he said. "The industry is now moving rapidly into a new and less certain environment where arguably, another revolutionary change is required in order to continue sustaining it. The potential challenges include technical, economical, license to operate, and human capital issues. As was the case in the late 1970s when hard ore rock was first encountered, the industry must now change in order to sustain itself technical- ly and economically." Certainly there is strong justification for some radical new approaches, especially as future block caves will be in even hard- er rock, at greater depths. Add in chal- lenges such as water inflows, high-virgin rock temperatures and ventilation require- ments, and it is easy to see that companies are going to have to be highly innovative in their approach. Deeper mines also bring with them higher capex requirements, in an industry where developing a big block cave is already only within the grasp of those with deep pockets. Nonetheless, the incentive is there, and as past experience has shown, new con- cepts and technologies may take time to develop to their full potential, but they are very effective when they get there. JULY 2014 • E&MJ; 37 www.e-mj.com B LO C K C A V I N G EMJ_pg32-37_EMJ_pg32-37 7/2/14 8:35 AM Page 37